A market-wide average across qualities and sizes. Your stone's value depends on carat, color, clarity, cut, treatment, and origin.
Sardonyx is a variety of banded chalcedony composed of layers of sard (reddish-brown chalcedony) and onyx (white or lighter chalcedony). It combines earthy red-brown and white or cream bands in straight or slightly curved layers. With Mohs hardness 6.5–7 and good toughness, sardonyx is suitable for cameos, intaglios, cabochons and beads.
Market averages will not price your stone. GemstoneAI identifies gems and jewelry from a photo, checks authenticity and treatment signals, and gives you a real market valuation in seconds. Free to try.
The GemstoneAI market index for sardonyx is $5.96 per carat as of 2026-08-04. That is a market-wide average across qualities, not a quote for a specific stone. Individual value depends on carat, color, clarity, cut, treatment, and origin.
Visual tests alone are unreliable. GemstoneAI analyzes a photo of your stone for identity, treatment indicators, and authenticity signals, then estimates market value. It is free to try.
Gem prices move on supply, demand, and metal markets; treat any single stone as a collectible first and an asset second.